diff options
author | Kees Cook <keescook@chromium.org> | 2018-03-06 14:58:09 -0800 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-03-06 19:18:55 -0800 |
commit | 039a1c42058db54692a6d4497508bd48555f29fb (patch) | |
tree | 0fbd5a504e8a3cdf0cffd7e6bd0c41332f3e55d0 /drivers/misc/lkdtm | |
parent | 37b96a4931dba07cebbf07092e55d1562155412b (diff) | |
download | linux-039a1c42058db54692a6d4497508bd48555f29fb.tar.gz linux-039a1c42058db54692a6d4497508bd48555f29fb.tar.bz2 linux-039a1c42058db54692a6d4497508bd48555f29fb.zip |
lkdtm: Relocate code to subdirectory
The LKDTM modules keep expanding, and it's getting weird to have each file
get a prefix. Instead, move to a subdirectory for cleaner handling.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/misc/lkdtm')
-rw-r--r-- | drivers/misc/lkdtm/Makefile | 20 | ||||
-rw-r--r-- | drivers/misc/lkdtm/bugs.c | 257 | ||||
-rw-r--r-- | drivers/misc/lkdtm/core.c | 505 | ||||
-rw-r--r-- | drivers/misc/lkdtm/heap.c | 148 | ||||
-rw-r--r-- | drivers/misc/lkdtm/lkdtm.h | 86 | ||||
-rw-r--r-- | drivers/misc/lkdtm/perms.c | 203 | ||||
-rw-r--r-- | drivers/misc/lkdtm/refcount.c | 400 | ||||
-rw-r--r-- | drivers/misc/lkdtm/rodata.c | 11 | ||||
-rw-r--r-- | drivers/misc/lkdtm/usercopy.c | 339 |
9 files changed, 1969 insertions, 0 deletions
diff --git a/drivers/misc/lkdtm/Makefile b/drivers/misc/lkdtm/Makefile new file mode 100644 index 000000000000..3370a4138e94 --- /dev/null +++ b/drivers/misc/lkdtm/Makefile @@ -0,0 +1,20 @@ +# SPDX-License-Identifier: GPL-2.0 +obj-$(CONFIG_LKDTM) += lkdtm.o + +lkdtm-$(CONFIG_LKDTM) += core.o +lkdtm-$(CONFIG_LKDTM) += bugs.o +lkdtm-$(CONFIG_LKDTM) += heap.o +lkdtm-$(CONFIG_LKDTM) += perms.o +lkdtm-$(CONFIG_LKDTM) += refcount.o +lkdtm-$(CONFIG_LKDTM) += rodata_objcopy.o +lkdtm-$(CONFIG_LKDTM) += usercopy.o + +KCOV_INSTRUMENT_rodata.o := n + +OBJCOPYFLAGS := +OBJCOPYFLAGS_rodata_objcopy.o := \ + --set-section-flags .text=alloc,readonly \ + --rename-section .text=.rodata +targets += rodata.o rodata_objcopy.o +$(obj)/rodata_objcopy.o: $(obj)/rodata.o FORCE + $(call if_changed,objcopy) diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c new file mode 100644 index 000000000000..7eebbdfbcacd --- /dev/null +++ b/drivers/misc/lkdtm/bugs.c @@ -0,0 +1,257 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This is for all the tests related to logic bugs (e.g. bad dereferences, + * bad alignment, bad loops, bad locking, bad scheduling, deep stacks, and + * lockups) along with other things that don't fit well into existing LKDTM + * test source files. + */ +#include "lkdtm.h" +#include <linux/list.h> +#include <linux/sched.h> +#include <linux/sched/signal.h> +#include <linux/sched/task_stack.h> +#include <linux/uaccess.h> + +struct lkdtm_list { + struct list_head node; +}; + +/* + * Make sure our attempts to over run the kernel stack doesn't trigger + * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we + * recurse past the end of THREAD_SIZE by default. + */ +#if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0) +#define REC_STACK_SIZE (CONFIG_FRAME_WARN / 2) +#else +#define REC_STACK_SIZE (THREAD_SIZE / 8) +#endif +#define REC_NUM_DEFAULT ((THREAD_SIZE / REC_STACK_SIZE) * 2) + +static int recur_count = REC_NUM_DEFAULT; + +static DEFINE_SPINLOCK(lock_me_up); + +static int recursive_loop(int remaining) +{ + char buf[REC_STACK_SIZE]; + + /* Make sure compiler does not optimize this away. */ + memset(buf, (remaining & 0xff) | 0x1, REC_STACK_SIZE); + if (!remaining) + return 0; + else + return recursive_loop(remaining - 1); +} + +/* If the depth is negative, use the default, otherwise keep parameter. */ +void __init lkdtm_bugs_init(int *recur_param) +{ + if (*recur_param < 0) + *recur_param = recur_count; + else + recur_count = *recur_param; +} + +void lkdtm_PANIC(void) +{ + panic("dumptest"); +} + +void lkdtm_BUG(void) +{ + BUG(); +} + +static int warn_counter; + +void lkdtm_WARNING(void) +{ + WARN(1, "Warning message trigger count: %d\n", warn_counter++); +} + +void lkdtm_EXCEPTION(void) +{ + *((volatile int *) 0) = 0; +} + +void lkdtm_LOOP(void) +{ + for (;;) + ; +} + +void lkdtm_OVERFLOW(void) +{ + (void) recursive_loop(recur_count); +} + +static noinline void __lkdtm_CORRUPT_STACK(void *stack) +{ + memset(stack, '\xff', 64); +} + +/* This should trip the stack canary, not corrupt the return address. */ +noinline void lkdtm_CORRUPT_STACK(void) +{ + /* Use default char array length that triggers stack protection. */ + char data[8] __aligned(sizeof(void *)); + + __lkdtm_CORRUPT_STACK(&data); + + pr_info("Corrupted stack containing char array ...\n"); +} + +/* Same as above but will only get a canary with -fstack-protector-strong */ +noinline void lkdtm_CORRUPT_STACK_STRONG(void) +{ + union { + unsigned short shorts[4]; + unsigned long *ptr; + } data __aligned(sizeof(void *)); + + __lkdtm_CORRUPT_STACK(&data); + + pr_info("Corrupted stack containing union ...\n"); +} + +void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void) +{ + static u8 data[5] __attribute__((aligned(4))) = {1, 2, 3, 4, 5}; + u32 *p; + u32 val = 0x12345678; + + p = (u32 *)(data + 1); + if (*p == 0) + val = 0x87654321; + *p = val; +} + +void lkdtm_SOFTLOCKUP(void) +{ + preempt_disable(); + for (;;) + cpu_relax(); +} + +void lkdtm_HARDLOCKUP(void) +{ + local_irq_disable(); + for (;;) + cpu_relax(); +} + +void lkdtm_SPINLOCKUP(void) +{ + /* Must be called twice to trigger. */ + spin_lock(&lock_me_up); + /* Let sparse know we intended to exit holding the lock. */ + __release(&lock_me_up); +} + +void lkdtm_HUNG_TASK(void) +{ + set_current_state(TASK_UNINTERRUPTIBLE); + schedule(); +} + +void lkdtm_CORRUPT_LIST_ADD(void) +{ + /* + * Initially, an empty list via LIST_HEAD: + * test_head.next = &test_head + * test_head.prev = &test_head + */ + LIST_HEAD(test_head); + struct lkdtm_list good, bad; + void *target[2] = { }; + void *redirection = ⌖ + + pr_info("attempting good list addition\n"); + + /* + * Adding to the list performs these actions: + * test_head.next->prev = &good.node + * good.node.next = test_head.next + * good.node.prev = test_head + * test_head.next = good.node + */ + list_add(&good.node, &test_head); + + pr_info("attempting corrupted list addition\n"); + /* + * In simulating this "write what where" primitive, the "what" is + * the address of &bad.node, and the "where" is the address held + * by "redirection". + */ + test_head.next = redirection; + list_add(&bad.node, &test_head); + + if (target[0] == NULL && target[1] == NULL) + pr_err("Overwrite did not happen, but no BUG?!\n"); + else + pr_err("list_add() corruption not detected!\n"); +} + +void lkdtm_CORRUPT_LIST_DEL(void) +{ + LIST_HEAD(test_head); + struct lkdtm_list item; + void *target[2] = { }; + void *redirection = ⌖ + + list_add(&item.node, &test_head); + + pr_info("attempting good list removal\n"); + list_del(&item.node); + + pr_info("attempting corrupted list removal\n"); + list_add(&item.node, &test_head); + + /* As with the list_add() test above, this corrupts "next". */ + item.node.next = redirection; + list_del(&item.node); + + if (target[0] == NULL && target[1] == NULL) + pr_err("Overwrite did not happen, but no BUG?!\n"); + else + pr_err("list_del() corruption not detected!\n"); +} + +/* Test if unbalanced set_fs(KERNEL_DS)/set_fs(USER_DS) check exists. */ +void lkdtm_CORRUPT_USER_DS(void) +{ + pr_info("setting bad task size limit\n"); + set_fs(KERNEL_DS); + + /* Make sure we do not keep running with a KERNEL_DS! */ + force_sig(SIGKILL, current); +} + +/* Test that VMAP_STACK is actually allocating with a leading guard page */ +void lkdtm_STACK_GUARD_PAGE_LEADING(void) +{ + const unsigned char *stack = task_stack_page(current); + const unsigned char *ptr = stack - 1; + volatile unsigned char byte; + + pr_info("attempting bad read from page below current stack\n"); + + byte = *ptr; + + pr_err("FAIL: accessed page before stack!\n"); +} + +/* Test that VMAP_STACK is actually allocating with a trailing guard page */ +void lkdtm_STACK_GUARD_PAGE_TRAILING(void) +{ + const unsigned char *stack = task_stack_page(current); + const unsigned char *ptr = stack + THREAD_SIZE; + volatile unsigned char byte; + + pr_info("attempting bad read from page above current stack\n"); + + byte = *ptr; + + pr_err("FAIL: accessed page after stack!\n"); +} diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c new file mode 100644 index 000000000000..2154d1bfd18b --- /dev/null +++ b/drivers/misc/lkdtm/core.c @@ -0,0 +1,505 @@ +/* + * Linux Kernel Dump Test Module for testing kernel crashes conditions: + * induces system failures at predefined crashpoints and under predefined + * operational conditions in order to evaluate the reliability of kernel + * sanity checking and crash dumps obtained using different dumping + * solutions. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright (C) IBM Corporation, 2006 + * + * Author: Ankita Garg <ankita@in.ibm.com> + * + * It is adapted from the Linux Kernel Dump Test Tool by + * Fernando Luis Vazquez Cao <http://lkdtt.sourceforge.net> + * + * Debugfs support added by Simon Kagstrom <simon.kagstrom@netinsight.net> + * + * See Documentation/fault-injection/provoke-crashes.txt for instructions + */ +#include "lkdtm.h" +#include <linux/fs.h> +#include <linux/module.h> +#include <linux/buffer_head.h> +#include <linux/kprobes.h> +#include <linux/list.h> +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/hrtimer.h> +#include <linux/slab.h> +#include <scsi/scsi_cmnd.h> +#include <linux/debugfs.h> + +#ifdef CONFIG_IDE +#include <linux/ide.h> +#endif + +#define DEFAULT_COUNT 10 + +static int lkdtm_debugfs_open(struct inode *inode, struct file *file); +static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf, + size_t count, loff_t *off); +static ssize_t direct_entry(struct file *f, const char __user *user_buf, + size_t count, loff_t *off); + +#ifdef CONFIG_KPROBES +static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs); +static ssize_t lkdtm_debugfs_entry(struct file *f, + const char __user *user_buf, + size_t count, loff_t *off); +# define CRASHPOINT_KPROBE(_symbol) \ + .kprobe = { \ + .symbol_name = (_symbol), \ + .pre_handler = lkdtm_kprobe_handler, \ + }, +# define CRASHPOINT_WRITE(_symbol) \ + (_symbol) ? lkdtm_debugfs_entry : direct_entry +#else +# define CRASHPOINT_KPROBE(_symbol) +# define CRASHPOINT_WRITE(_symbol) direct_entry +#endif + +/* Crash points */ +struct crashpoint { + const char *name; + const struct file_operations fops; + struct kprobe kprobe; +}; + +#define CRASHPOINT(_name, _symbol) \ + { \ + .name = _name, \ + .fops = { \ + .read = lkdtm_debugfs_read, \ + .llseek = generic_file_llseek, \ + .open = lkdtm_debugfs_open, \ + .write = CRASHPOINT_WRITE(_symbol) \ + }, \ + CRASHPOINT_KPROBE(_symbol) \ + } + +/* Define the possible places where we can trigger a crash point. */ +static struct crashpoint crashpoints[] = { + CRASHPOINT("DIRECT", NULL), +#ifdef CONFIG_KPROBES + CRASHPOINT("INT_HARDWARE_ENTRY", "do_IRQ"), + CRASHPOINT("INT_HW_IRQ_EN", "handle_irq_event"), + CRASHPOINT("INT_TASKLET_ENTRY", "tasklet_action"), + CRASHPOINT("FS_DEVRW", "ll_rw_block"), + CRASHPOINT("MEM_SWAPOUT", "shrink_inactive_list"), + CRASHPOINT("TIMERADD", "hrtimer_start"), + CRASHPOINT("SCSI_DISPATCH_CMD", "scsi_dispatch_cmd"), +# ifdef CONFIG_IDE + CRASHPOINT("IDE_CORE_CP", "generic_ide_ioctl"), +# endif +#endif +}; + + +/* Crash types. */ +struct crashtype { + const char *name; + void (*func)(void); +}; + +#define CRASHTYPE(_name) \ + { \ + .name = __stringify(_name), \ + .func = lkdtm_ ## _name, \ + } + +/* Define the possible types of crashes that can be triggered. */ +static const struct crashtype crashtypes[] = { + CRASHTYPE(PANIC), + CRASHTYPE(BUG), + CRASHTYPE(WARNING), + CRASHTYPE(EXCEPTION), + CRASHTYPE(LOOP), + CRASHTYPE(OVERFLOW), + CRASHTYPE(CORRUPT_LIST_ADD), + CRASHTYPE(CORRUPT_LIST_DEL), + CRASHTYPE(CORRUPT_USER_DS), + CRASHTYPE(CORRUPT_STACK), + CRASHTYPE(CORRUPT_STACK_STRONG), + CRASHTYPE(STACK_GUARD_PAGE_LEADING), + CRASHTYPE(STACK_GUARD_PAGE_TRAILING), + CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE), + CRASHTYPE(OVERWRITE_ALLOCATION), + CRASHTYPE(WRITE_AFTER_FREE), + CRASHTYPE(READ_AFTER_FREE), + CRASHTYPE(WRITE_BUDDY_AFTER_FREE), + CRASHTYPE(READ_BUDDY_AFTER_FREE), + CRASHTYPE(SOFTLOCKUP), + CRASHTYPE(HARDLOCKUP), + CRASHTYPE(SPINLOCKUP), + CRASHTYPE(HUNG_TASK), + CRASHTYPE(EXEC_DATA), + CRASHTYPE(EXEC_STACK), + CRASHTYPE(EXEC_KMALLOC), + CRASHTYPE(EXEC_VMALLOC), + CRASHTYPE(EXEC_RODATA), + CRASHTYPE(EXEC_USERSPACE), + CRASHTYPE(ACCESS_USERSPACE), + CRASHTYPE(WRITE_RO), + CRASHTYPE(WRITE_RO_AFTER_INIT), + CRASHTYPE(WRITE_KERN), + CRASHTYPE(REFCOUNT_INC_OVERFLOW), + CRASHTYPE(REFCOUNT_ADD_OVERFLOW), + CRASHTYPE(REFCOUNT_INC_NOT_ZERO_OVERFLOW), + CRASHTYPE(REFCOUNT_ADD_NOT_ZERO_OVERFLOW), + CRASHTYPE(REFCOUNT_DEC_ZERO), + CRASHTYPE(REFCOUNT_DEC_NEGATIVE), + CRASHTYPE(REFCOUNT_DEC_AND_TEST_NEGATIVE), + CRASHTYPE(REFCOUNT_SUB_AND_TEST_NEGATIVE), + CRASHTYPE(REFCOUNT_INC_ZERO), + CRASHTYPE(REFCOUNT_ADD_ZERO), + CRASHTYPE(REFCOUNT_INC_SATURATED), + CRASHTYPE(REFCOUNT_DEC_SATURATED), + CRASHTYPE(REFCOUNT_ADD_SATURATED), + CRASHTYPE(REFCOUNT_INC_NOT_ZERO_SATURATED), + CRASHTYPE(REFCOUNT_ADD_NOT_ZERO_SATURATED), + CRASHTYPE(REFCOUNT_DEC_AND_TEST_SATURATED), + CRASHTYPE(REFCOUNT_SUB_AND_TEST_SATURATED), + CRASHTYPE(REFCOUNT_TIMING), + CRASHTYPE(ATOMIC_TIMING), + CRASHTYPE(USERCOPY_HEAP_SIZE_TO), + CRASHTYPE(USERCOPY_HEAP_SIZE_FROM), + CRASHTYPE(USERCOPY_HEAP_WHITELIST_TO), + CRASHTYPE(USERCOPY_HEAP_WHITELIST_FROM), + CRASHTYPE(USERCOPY_STACK_FRAME_TO), + CRASHTYPE(USERCOPY_STACK_FRAME_FROM), + CRASHTYPE(USERCOPY_STACK_BEYOND), + CRASHTYPE(USERCOPY_KERNEL), +}; + + +/* Global kprobe entry and crashtype. */ +static struct kprobe *lkdtm_kprobe; +static struct crashpoint *lkdtm_crashpoint; +static const struct crashtype *lkdtm_crashtype; + +/* Module parameters */ +static int recur_count = -1; +module_param(recur_count, int, 0644); +MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test"); + +static char* cpoint_name; +module_param(cpoint_name, charp, 0444); +MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed"); + +static char* cpoint_type; +module_param(cpoint_type, charp, 0444); +MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\ + "hitting the crash point"); + +static int cpoint_count = DEFAULT_COUNT; +module_param(cpoint_count, int, 0644); +MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\ + "crash point is to be hit to trigger action"); + + +/* Return the crashtype number or NULL if the name is invalid */ +static const struct crashtype *find_crashtype(const char *name) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(crashtypes); i++) { + if (!strcmp(name, crashtypes[i].name)) + return &crashtypes[i]; + } + + return NULL; +} + +/* + * This is forced noinline just so it distinctly shows up in the stackdump + * which makes validation of expected lkdtm crashes easier. + */ +static noinline void lkdtm_do_action(const struct crashtype *crashtype) +{ + if (WARN_ON(!crashtype || !crashtype->func)) + return; + crashtype->func(); +} + +static int lkdtm_register_cpoint(struct crashpoint *crashpoint, + const struct crashtype *crashtype) +{ + int ret; + + /* If this doesn't have a symbol, just call immediately. */ + if (!crashpoint->kprobe.symbol_name) { + lkdtm_do_action(crashtype); + return 0; + } + + if (lkdtm_kprobe != NULL) + unregister_kprobe(lkdtm_kprobe); + + lkdtm_crashpoint = crashpoint; + lkdtm_crashtype = crashtype; + lkdtm_kprobe = &crashpoint->kprobe; + ret = register_kprobe(lkdtm_kprobe); + if (ret < 0) { + pr_info("Couldn't register kprobe %s\n", + crashpoint->kprobe.symbol_name); + lkdtm_kprobe = NULL; + lkdtm_crashpoint = NULL; + lkdtm_crashtype = NULL; + } + + return ret; +} + +#ifdef CONFIG_KPROBES +/* Global crash counter and spinlock. */ +static int crash_count = DEFAULT_COUNT; +static DEFINE_SPINLOCK(crash_count_lock); + +/* Called by kprobe entry points. */ +static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs) +{ + unsigned long flags; + bool do_it = false; + + if (WARN_ON(!lkdtm_crashpoint || !lkdtm_crashtype)) + return 0; + + spin_lock_irqsave(&crash_count_lock, flags); + crash_count--; + pr_info("Crash point %s of type %s hit, trigger in %d rounds\n", + lkdtm_crashpoint->name, lkdtm_crashtype->name, crash_count); + + if (crash_count == 0) { + do_it = true; + crash_count = cpoint_count; + } + spin_unlock_irqrestore(&crash_count_lock, flags); + + if (do_it) + lkdtm_do_action(lkdtm_crashtype); + + return 0; +} + +static ssize_t lkdtm_debugfs_entry(struct file *f, + const char __user *user_buf, + size_t count, loff_t *off) +{ + struct crashpoint *crashpoint = file_inode(f)->i_private; + const struct crashtype *crashtype = NULL; + char *buf; + int err; + + if (count >= PAGE_SIZE) + return -EINVAL; + + buf = (char *)__get_free_page(GFP_KERNEL); + if (!buf) + return -ENOMEM; + if (copy_from_user(buf, user_buf, count)) { + free_page((unsigned long) buf); + return -EFAULT; + } + /* NULL-terminate and remove enter */ + buf[count] = '\0'; + strim(buf); + + crashtype = find_crashtype(buf); + free_page((unsigned long)buf); + + if (!crashtype) + return -EINVAL; + + err = lkdtm_register_cpoint(crashpoint, crashtype); + if (err < 0) + return err; + + *off += count; + + return count; +} +#endif + +/* Generic read callback that just prints out the available crash types */ +static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf, + size_t count, loff_t *off) +{ + char *buf; + int i, n, out; + + buf = (char *)__get_free_page(GFP_KERNEL); + if (buf == NULL) + return -ENOMEM; + + n = snprintf(buf, PAGE_SIZE, "Available crash types:\n"); + for (i = 0; i < ARRAY_SIZE(crashtypes); i++) { + n += snprintf(buf + n, PAGE_SIZE - n, "%s\n", + crashtypes[i].name); + } + buf[n] = '\0'; + + out = simple_read_from_buffer(user_buf, count, off, + buf, n); + free_page((unsigned long) buf); + + return out; +} + +static int lkdtm_debugfs_open(struct inode *inode, struct file *file) +{ + return 0; +} + +/* Special entry to just crash directly. Available without KPROBEs */ +static ssize_t direct_entry(struct file *f, const char __user *user_buf, + size_t count, loff_t *off) +{ + const struct crashtype *crashtype; + char *buf; + + if (count >= PAGE_SIZE) + return -EINVAL; + if (count < 1) + return -EINVAL; + + buf = (char *)__get_free_page(GFP_KERNEL); + if (!buf) + return -ENOMEM; + if (copy_from_user(buf, user_buf, count)) { + free_page((unsigned long) buf); + return -EFAULT; + } + /* NULL-terminate and remove enter */ + buf[count] = '\0'; + strim(buf); + + crashtype = find_crashtype(buf); + free_page((unsigned long) buf); + if (!crashtype) + return -EINVAL; + + pr_info("Performing direct entry %s\n", crashtype->name); + lkdtm_do_action(crashtype); + *off += count; + + return count; +} + +static struct dentry *lkdtm_debugfs_root; + +static int __init lkdtm_module_init(void) +{ + struct crashpoint *crashpoint = NULL; + const struct crashtype *crashtype = NULL; + int ret = -EINVAL; + int i; + + /* Neither or both of these need to be set */ + if ((cpoint_type || cpoint_name) && !(cpoint_type && cpoint_name)) { + pr_err("Need both cpoint_type and cpoint_name or neither\n"); + return -EINVAL; + } + + if (cpoint_type) { + crashtype = find_crashtype(cpoint_type); + if (!crashtype) { + pr_err("Unknown crashtype '%s'\n", cpoint_type); + return -EINVAL; + } + } + + if (cpoint_name) { + for (i = 0; i < ARRAY_SIZE(crashpoints); i++) { + if (!strcmp(cpoint_name, crashpoints[i].name)) + crashpoint = &crashpoints[i]; + } + + /* Refuse unknown crashpoints. */ + if (!crashpoint) { + pr_err("Invalid crashpoint %s\n", cpoint_name); + return -EINVAL; + } + } + +#ifdef CONFIG_KPROBES + /* Set crash count. */ + crash_count = cpoint_count; +#endif + + /* Handle test-specific initialization. */ + lkdtm_bugs_init(&recur_count); + lkdtm_perms_init(); + lkdtm_usercopy_init(); + + /* Register debugfs interface */ + lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL); + if (!lkdtm_debugfs_root) { + pr_err("creating root dir failed\n"); + return -ENODEV; + } + + /* Install debugfs trigger files. */ + for (i = 0; i < ARRAY_SIZE(crashpoints); i++) { + struct crashpoint *cur = &crashpoints[i]; + struct dentry *de; + + de = debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root, + cur, &cur->fops); + if (de == NULL) { + pr_err("could not create crashpoint %s\n", cur->name); + goto out_err; + } + } + + /* Install crashpoint if one was selected. */ + if (crashpoint) { + ret = lkdtm_register_cpoint(crashpoint, crashtype); + if (ret < 0) { + pr_info("Invalid crashpoint %s\n", crashpoint->name); + goto out_err; + } + pr_info("Crash point %s of type %s registered\n", + crashpoint->name, cpoint_type); + } else { + pr_info("No crash points registered, enable through debugfs\n"); + } + + return 0; + +out_err: + debugfs_remove_recursive(lkdtm_debugfs_root); + return ret; +} + +static void __exit lkdtm_module_exit(void) +{ + debugfs_remove_recursive(lkdtm_debugfs_root); + + /* Handle test-specific clean-up. */ + lkdtm_usercopy_exit(); + + if (lkdtm_kprobe != NULL) + unregister_kprobe(lkdtm_kprobe); + + pr_info("Crash point unregistered\n"); +} + +module_init(lkdtm_module_init); +module_exit(lkdtm_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Kernel crash testing module"); diff --git a/drivers/misc/lkdtm/heap.c b/drivers/misc/lkdtm/heap.c new file mode 100644 index 000000000000..65026d7de130 --- /dev/null +++ b/drivers/misc/lkdtm/heap.c @@ -0,0 +1,148 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This is for all the tests relating directly to heap memory, including + * page allocation and slab allocations. + */ +#include "lkdtm.h" +#include <linux/slab.h> +#include <linux/sched.h> + +/* + * This tries to stay within the next largest power-of-2 kmalloc cache + * to avoid actually overwriting anything important if it's not detected + * correctly. + */ +void lkdtm_OVERWRITE_ALLOCATION(void) +{ + size_t len = 1020; + u32 *data = kmalloc(len, GFP_KERNEL); + if (!data) + return; + + data[1024 / sizeof(u32)] = 0x12345678; + kfree(data); +} + +void lkdtm_WRITE_AFTER_FREE(void) +{ + int *base, *again; + size_t len = 1024; + /* + * The slub allocator uses the first word to store the free + * pointer in some configurations. Use the middle of the + * allocation to avoid running into the freelist + */ + size_t offset = (len / sizeof(*base)) / 2; + + base = kmalloc(len, GFP_KERNEL); + if (!base) + return; + pr_info("Allocated memory %p-%p\n", base, &base[offset * 2]); + pr_info("Attempting bad write to freed memory at %p\n", + &base[offset]); + kfree(base); + base[offset] = 0x0abcdef0; + /* Attempt to notice the overwrite. */ + again = kmalloc(len, GFP_KERNEL); + kfree(again); + if (again != base) + pr_info("Hmm, didn't get the same memory range.\n"); +} + +void lkdtm_READ_AFTER_FREE(void) +{ + int *base, *val, saw; + size_t len = 1024; + /* + * The slub allocator uses the first word to store the free + * pointer in some configurations. Use the middle of the + * allocation to avoid running into the freelist + */ + size_t offset = (len / sizeof(*base)) / 2; + + base = kmalloc(len, GFP_KERNEL); + if (!base) { + pr_info("Unable to allocate base memory.\n"); + return; + } + + val = kmalloc(len, GFP_KERNEL); + if (!val) { + pr_info("Unable to allocate val memory.\n"); + kfree(base); + return; + } + + *val = 0x12345678; + base[offset] = *val; + pr_info("Value in memory before free: %x\n", base[offset]); + + kfree(base); + + pr_info("Attempting bad read from freed memory\n"); + saw = base[offset]; + if (saw != *val) { + /* Good! Poisoning happened, so declare a win. */ + pr_info("Memory correctly poisoned (%x)\n", saw); + BUG(); + } + pr_info("Memory was not poisoned\n"); + + kfree(val); +} + +void lkdtm_WRITE_BUDDY_AFTER_FREE(void) +{ + unsigned long p = __get_free_page(GFP_KERNEL); + if (!p) { + pr_info("Unable to allocate free page\n"); + return; + } + + pr_info("Writing to the buddy page before free\n"); + memset((void *)p, 0x3, PAGE_SIZE); + free_page(p); + schedule(); + pr_info("Attempting bad write to the buddy page after free\n"); + memset((void *)p, 0x78, PAGE_SIZE); + /* Attempt to notice the overwrite. */ + p = __get_free_page(GFP_KERNEL); + free_page(p); + schedule(); +} + +void lkdtm_READ_BUDDY_AFTER_FREE(void) +{ + unsigned long p = __get_free_page(GFP_KERNEL); + int saw, *val; + int *base; + + if (!p) { + pr_info("Unable to allocate free page\n"); + return; + } + + val = kmalloc(1024, GFP_KERNEL); + if (!val) { + pr_info("Unable to allocate val memory.\n"); + free_page(p); + return; + } + + base = (int *)p; + + *val = 0x12345678; + base[0] = *val; + pr_info("Value in memory before free: %x\n", base[0]); + free_page(p); + pr_info("Attempting to read from freed memory\n"); + saw = base[0]; + if (saw != *val) { + /* Good! Poisoning happened, so declare a win. */ + pr_info("Memory correctly poisoned (%x)\n", saw); + BUG(); + } + pr_info("Buddy page was not poisoned\n"); + + kfree(val); +} diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h new file mode 100644 index 000000000000..9e513dcfd809 --- /dev/null +++ b/drivers/misc/lkdtm/lkdtm.h @@ -0,0 +1,86 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __LKDTM_H +#define __LKDTM_H + +#define pr_fmt(fmt) "lkdtm: " fmt + +#include <linux/kernel.h> + +/* lkdtm_bugs.c */ +void __init lkdtm_bugs_init(int *recur_param); +void lkdtm_PANIC(void); +void lkdtm_BUG(void); +void lkdtm_WARNING(void); +void lkdtm_EXCEPTION(void); +void lkdtm_LOOP(void); +void lkdtm_OVERFLOW(void); +void lkdtm_CORRUPT_STACK(void); +void lkdtm_CORRUPT_STACK_STRONG(void); +void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void); +void lkdtm_SOFTLOCKUP(void); +void lkdtm_HARDLOCKUP(void); +void lkdtm_SPINLOCKUP(void); +void lkdtm_HUNG_TASK(void); +void lkdtm_CORRUPT_LIST_ADD(void); +void lkdtm_CORRUPT_LIST_DEL(void); +void lkdtm_CORRUPT_USER_DS(void); +void lkdtm_STACK_GUARD_PAGE_LEADING(void); +void lkdtm_STACK_GUARD_PAGE_TRAILING(void); + +/* lkdtm_heap.c */ +void lkdtm_OVERWRITE_ALLOCATION(void); +void lkdtm_WRITE_AFTER_FREE(void); +void lkdtm_READ_AFTER_FREE(void); +void lkdtm_WRITE_BUDDY_AFTER_FREE(void); +void lkdtm_READ_BUDDY_AFTER_FREE(void); + +/* lkdtm_perms.c */ +void __init lkdtm_perms_init(void); +void lkdtm_WRITE_RO(void); +void lkdtm_WRITE_RO_AFTER_INIT(void); +void lkdtm_WRITE_KERN(void); +void lkdtm_EXEC_DATA(void); +void lkdtm_EXEC_STACK(void); +void lkdtm_EXEC_KMALLOC(void); +void lkdtm_EXEC_VMALLOC(void); +void lkdtm_EXEC_RODATA(void); +void lkdtm_EXEC_USERSPACE(void); +void lkdtm_ACCESS_USERSPACE(void); + +/* lkdtm_refcount.c */ +void lkdtm_REFCOUNT_INC_OVERFLOW(void); +void lkdtm_REFCOUNT_ADD_OVERFLOW(void); +void lkdtm_REFCOUNT_INC_NOT_ZERO_OVERFLOW(void); +void lkdtm_REFCOUNT_ADD_NOT_ZERO_OVERFLOW(void); +void lkdtm_REFCOUNT_DEC_ZERO(void); +void lkdtm_REFCOUNT_DEC_NEGATIVE(void); +void lkdtm_REFCOUNT_DEC_AND_TEST_NEGATIVE(void); +void lkdtm_REFCOUNT_SUB_AND_TEST_NEGATIVE(void); +void lkdtm_REFCOUNT_INC_ZERO(void); +void lkdtm_REFCOUNT_ADD_ZERO(void); +void lkdtm_REFCOUNT_INC_SATURATED(void); +void lkdtm_REFCOUNT_DEC_SATURATED(void); +void lkdtm_REFCOUNT_ADD_SATURATED(void); +void lkdtm_REFCOUNT_INC_NOT_ZERO_SATURATED(void); +void lkdtm_REFCOUNT_ADD_NOT_ZERO_SATURATED(void); +void lkdtm_REFCOUNT_DEC_AND_TEST_SATURATED(void); +void lkdtm_REFCOUNT_SUB_AND_TEST_SATURATED(void); +void lkdtm_REFCOUNT_TIMING(void); +void lkdtm_ATOMIC_TIMING(void); + +/* lkdtm_rodata.c */ +void lkdtm_rodata_do_nothing(void); + +/* lkdtm_usercopy.c */ +void __init lkdtm_usercopy_init(void); +void __exit lkdtm_usercopy_exit(void); +void lkdtm_USERCOPY_HEAP_SIZE_TO(void); +void lkdtm_USERCOPY_HEAP_SIZE_FROM(void); +void lkdtm_USERCOPY_HEAP_WHITELIST_TO(void); +void lkdtm_USERCOPY_HEAP_WHITELIST_FROM(void); +void lkdtm_USERCOPY_STACK_FRAME_TO(void); +void lkdtm_USERCOPY_STACK_FRAME_FROM(void); +void lkdtm_USERCOPY_STACK_BEYOND(void); +void lkdtm_USERCOPY_KERNEL(void); + +#endif diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c new file mode 100644 index 000000000000..53b85c9d16b8 --- /dev/null +++ b/drivers/misc/lkdtm/perms.c @@ -0,0 +1,203 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This is for all the tests related to validating kernel memory + * permissions: non-executable regions, non-writable regions, and + * even non-readable regions. + */ +#include "lkdtm.h" +#include <linux/slab.h> +#include <linux/vmalloc.h> +#include <linux/mman.h> +#include <linux/uaccess.h> +#include <asm/cacheflush.h> + +/* Whether or not to fill the target memory area with do_nothing(). */ +#define CODE_WRITE true +#define CODE_AS_IS false + +/* How many bytes to copy to be sure we've copied enough of do_nothing(). */ +#define EXEC_SIZE 64 + +/* This is non-const, so it will end up in the .data section. */ +static u8 data_area[EXEC_SIZE]; + +/* This is cost, so it will end up in the .rodata section. */ +static const unsigned long rodata = 0xAA55AA55; + +/* This is marked __ro_after_init, so it should ultimately be .rodata. */ +static unsigned long ro_after_init __ro_after_init = 0x55AA5500; + +/* + * This just returns to the caller. It is designed to be copied into + * non-executable memory regions. + */ +static void do_nothing(void) +{ + return; +} + +/* Must immediately follow do_nothing for size calculuations to work out. */ +static void do_overwritten(void) +{ + pr_info("do_overwritten wasn't overwritten!\n"); + return; +} + +static noinline void execute_location(void *dst, bool write) +{ + void (*func)(void) = dst; + + pr_info("attempting ok execution at %p\n", do_nothing); + do_nothing(); + + if (write == CODE_WRITE) { + memcpy(dst, do_nothing, EXEC_SIZE); + flush_icache_range((unsigned long)dst, + (unsigned long)dst + EXEC_SIZE); + } + pr_info("attempting bad execution at %p\n", func); + func(); +} + +static void execute_user_location(void *dst) +{ + int copied; + + /* Intentionally crossing kernel/user memory boundary. */ + void (*func)(void) = dst; + + pr_info("attempting ok execution at %p\n", do_nothing); + do_nothing(); + + copied = access_process_vm(current, (unsigned long)dst, do_nothing, + EXEC_SIZE, FOLL_WRITE); + if (copied < EXEC_SIZE) + return; + pr_info("attempting bad execution at %p\n", func); + func(); +} + +void lkdtm_WRITE_RO(void) +{ + /* Explicitly cast away "const" for the test. */ + unsigned long *ptr = (unsigned long *)&rodata; + + pr_info("attempting bad rodata write at %p\n", ptr); + *ptr ^= 0xabcd1234; +} + +void lkdtm_WRITE_RO_AFTER_INIT(void) +{ + unsigned long *ptr = &ro_after_init; + + /* + * Verify we were written to during init. Since an Oops + * is considered a "success", a failure is to just skip the + * real test. + */ + if ((*ptr & 0xAA) != 0xAA) { + pr_info("%p was NOT written during init!?\n", ptr); + return; + } + + pr_info("attempting bad ro_after_init write at %p\n", ptr); + *ptr ^= 0xabcd1234; +} + +void lkdtm_WRITE_KERN(void) +{ + size_t size; + unsigned char *ptr; + + size = (unsigned long)do_overwritten - (unsigned long)do_nothing; + ptr = (unsigned char *)do_overwritten; + + pr_info("attempting bad %zu byte write at %p\n", size, ptr); + memcpy(ptr, (unsigned char *)do_nothing, size); + flush_icache_range((unsigned long)ptr, (unsigned long)(ptr + size)); + + do_overwritten(); +} + +void lkdtm_EXEC_DATA(void) +{ + execute_location(data_area, CODE_WRITE); +} + +void lkdtm_EXEC_STACK(void) +{ + u8 stack_area[EXEC_SIZE]; + execute_location(stack_area, CODE_WRITE); +} + +void lkdtm_EXEC_KMALLOC(void) +{ + u32 *kmalloc_area = kmalloc(EXEC_SIZE, GFP_KERNEL); + execute_location(kmalloc_area, CODE_WRITE); + kfree(kmalloc_area); +} + +void lkdtm_EXEC_VMALLOC(void) +{ + u32 *vmalloc_area = vmalloc(EXEC_SIZE); + execute_location(vmalloc_area, CODE_WRITE); + vfree(vmalloc_area); +} + +void lkdtm_EXEC_RODATA(void) +{ + execute_location(lkdtm_rodata_do_nothing, CODE_AS_IS); +} + +void lkdtm_EXEC_USERSPACE(void) +{ + unsigned long user_addr; + + user_addr = vm_mmap(NULL, 0, PAGE_SIZE, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_ANONYMOUS | MAP_PRIVATE, 0); + if (user_addr >= TASK_SIZE) { + pr_warn("Failed to allocate user memory\n"); + return; + } + execute_user_location((void *)user_addr); + vm_munmap(user_addr, PAGE_SIZE); +} + +void lkdtm_ACCESS_USERSPACE(void) +{ + unsigned long user_addr, tmp = 0; + unsigned long *ptr; + + user_addr = vm_mmap(NULL, 0, PAGE_SIZE, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_ANONYMOUS | MAP_PRIVATE, 0); + if (user_addr >= TASK_SIZE) { + pr_warn("Failed to allocate user memory\n"); + return; + } + + if (copy_to_user((void __user *)user_addr, &tmp, sizeof(tmp))) { + pr_warn("copy_to_user failed\n"); + vm_munmap(user_addr, PAGE_SIZE); + return; + } + + ptr = (unsigned long *)user_addr; + + pr_info("attempting bad read at %p\n", ptr); + tmp = *ptr; + tmp += 0xc0dec0de; + + pr_info("attempting bad write at %p\n", ptr); + *ptr = tmp; + + vm_munmap(user_addr, PAGE_SIZE); +} + +void __init lkdtm_perms_init(void) +{ + /* Make sure we can write to __ro_after_init values during __init */ + ro_after_init |= 0xAA; + +} diff --git a/drivers/misc/lkdtm/refcount.c b/drivers/misc/lkdtm/refcount.c new file mode 100644 index 000000000000..2b99d448e7fd --- /dev/null +++ b/drivers/misc/lkdtm/refcount.c @@ -0,0 +1,400 @@ +/* + * This is for all the tests related to refcount bugs (e.g. overflow, + * underflow, reaching zero untested, etc). + */ +#include "lkdtm.h" +#include <linux/refcount.h> + +#ifdef CONFIG_REFCOUNT_FULL +#define REFCOUNT_MAX (UINT_MAX - 1) +#define REFCOUNT_SATURATED UINT_MAX +#else +#define REFCOUNT_MAX INT_MAX +#define REFCOUNT_SATURATED (INT_MIN / 2) +#endif + +static void overflow_check(refcount_t *ref) +{ + switch (refcount_read(ref)) { + case REFCOUNT_SATURATED: + pr_info("Overflow detected: saturated\n"); + break; + case REFCOUNT_MAX: + pr_warn("Overflow detected: unsafely reset to max\n"); + break; + default: + pr_err("Fail: refcount wrapped to %d\n", refcount_read(ref)); + } +} + +/* + * A refcount_inc() above the maximum value of the refcount implementation, + * should at least saturate, and at most also WARN. + */ +void lkdtm_REFCOUNT_INC_OVERFLOW(void) +{ + refcount_t over = REFCOUNT_INIT(REFCOUNT_MAX - 1); + + pr_info("attempting good refcount_inc() without overflow\n"); + refcount_dec(&over); + refcount_inc(&over); + + pr_info("attempting bad refcount_inc() overflow\n"); + refcount_inc(&over); + refcount_inc(&over); + + overflow_check(&over); +} + +/* refcount_add() should behave just like refcount_inc() above. */ +void lkdtm_REFCOUNT_ADD_OVERFLOW(void) +{ + refcount_t over = REFCOUNT_INIT(REFCOUNT_MAX - 1); + + pr_info("attempting good refcount_add() without overflow\n"); + refcount_dec(&over); + refcount_dec(&over); + refcount_dec(&over); + refcount_dec(&over); + refcount_add(4, &over); + + pr_info("attempting bad refcount_add() overflow\n"); + refcount_add(4, &over); + + overflow_check(&over); +} + +/* refcount_inc_not_zero() should behave just like refcount_inc() above. */ +void lkdtm_REFCOUNT_INC_NOT_ZERO_OVERFLOW(void) +{ + refcount_t over = REFCOUNT_INIT(REFCOUNT_MAX); + + pr_info("attempting bad refcount_inc_not_zero() overflow\n"); + if (!refcount_inc_not_zero(&over)) + pr_warn("Weird: refcount_inc_not_zero() reported zero\n"); + + overflow_check(&over); +} + +/* refcount_add_not_zero() should behave just like refcount_inc() above. */ +void lkdtm_REFCOUNT_ADD_NOT_ZERO_OVERFLOW(void) +{ + refcount_t over = REFCOUNT_INIT(REFCOUNT_MAX); + + pr_info("attempting bad refcount_add_not_zero() overflow\n"); + if (!refcount_add_not_zero(6, &over)) + pr_warn("Weird: refcount_add_not_zero() reported zero\n"); + + overflow_check(&over); +} + +static void check_zero(refcount_t *ref) +{ + switch (refcount_read(ref)) { + case REFCOUNT_SATURATED: + pr_info("Zero detected: saturated\n"); + break; + case REFCOUNT_MAX: + pr_warn("Zero detected: unsafely reset to max\n"); + break; + case 0: + pr_warn("Still at zero: refcount_inc/add() must not inc-from-0\n"); + break; + default: + pr_err("Fail: refcount went crazy: %d\n", refcount_read(ref)); + } +} + +/* + * A refcount_dec(), as opposed to a refcount_dec_and_test(), when it hits + * zero it should either saturate (when inc-from-zero isn't protected) + * or stay at zero (when inc-from-zero is protected) and should WARN for both. + */ +void lkdtm_REFCOUNT_DEC_ZERO(void) +{ + refcount_t zero = REFCOUNT_INIT(2); + + pr_info("attempting good refcount_dec()\n"); + refcount_dec(&zero); + + pr_info("attempting bad refcount_dec() to zero\n"); + refcount_dec(&zero); + + check_zero(&zero); +} + +static void check_negative(refcount_t *ref, int start) +{ + /* + * CONFIG_REFCOUNT_FULL refuses to move a refcount at all on an + * over-sub, so we have to track our starting position instead of + * looking only at zero-pinning. + */ + if (refcount_read(ref) == start) { + pr_warn("Still at %d: refcount_inc/add() must not inc-from-0\n", + start); + return; + } + + switch (refcount_read(ref)) { + case REFCOUNT_SATURATED: + pr_info("Negative detected: saturated\n"); + break; + case REFCOUNT_MAX: + pr_warn("Negative detected: unsafely reset to max\n"); + break; + default: + pr_err("Fail: refcount went crazy: %d\n", refcount_read(ref)); + } +} + +/* A refcount_dec() going negative should saturate and may WARN. */ +void lkdtm_REFCOUNT_DEC_NEGATIVE(void) +{ + refcount_t neg = REFCOUNT_INIT(0); + + pr_info("attempting bad refcount_dec() below zero\n"); + refcount_dec(&neg); + + check_negative(&neg, 0); +} + +/* + * A refcount_dec_and_test() should act like refcount_dec() above when + * going negative. + */ +void lkdtm_REFCOUNT_DEC_AND_TEST_NEGATIVE(void) +{ + refcount_t neg = REFCOUNT_INIT(0); + + pr_info("attempting bad refcount_dec_and_test() below zero\n"); + if (refcount_dec_and_test(&neg)) + pr_warn("Weird: refcount_dec_and_test() reported zero\n"); + + check_negative(&neg, 0); +} + +/* + * A refcount_sub_and_test() should act like refcount_dec_and_test() + * above when going negative. + */ +void lkdtm_REFCOUNT_SUB_AND_TEST_NEGATIVE(void) +{ + refcount_t neg = REFCOUNT_INIT(3); + + pr_info("attempting bad refcount_sub_and_test() below zero\n"); + if (refcount_sub_and_test(5, &neg)) + pr_warn("Weird: refcount_sub_and_test() reported zero\n"); + + check_negative(&neg, 3); +} + +static void check_from_zero(refcount_t *ref) +{ + switch (refcount_read(ref)) { + case 0: + pr_info("Zero detected: stayed at zero\n"); + break; + case REFCOUNT_SATURATED: + pr_info("Zero detected: saturated\n"); + break; + case REFCOUNT_MAX: + pr_warn("Zero detected: unsafely reset to max\n"); + break; + default: + pr_info("Fail: zero not detected, incremented to %d\n", + refcount_read(ref)); + } +} + +/* + * A refcount_inc() from zero should pin to zero or saturate and may WARN. + * Only CONFIG_REFCOUNT_FULL provides this protection currently. + */ +void lkdtm_REFCOUNT_INC_ZERO(void) +{ + refcount_t zero = REFCOUNT_INIT(0); + + pr_info("attempting safe refcount_inc_not_zero() from zero\n"); + if (!refcount_inc_not_zero(&zero)) { + pr_info("Good: zero detected\n"); + if (refcount_read(&zero) == 0) + pr_info("Correctly stayed at zero\n"); + else + pr_err("Fail: refcount went past zero!\n"); + } else { + pr_err("Fail: Zero not detected!?\n"); + } + + pr_info("attempting bad refcount_inc() from zero\n"); + refcount_inc(&zero); + + check_from_zero(&zero); +} + +/* + * A refcount_add() should act like refcount_inc() above when starting + * at zero. + */ +void lkdtm_REFCOUNT_ADD_ZERO(void) +{ + refcount_t zero = REFCOUNT_INIT(0); + + pr_info("attempting safe refcount_add_not_zero() from zero\n"); + if (!refcount_add_not_zero(3, &zero)) { + pr_info("Good: zero detected\n"); + if (refcount_read(&zero) == 0) + pr_info("Correctly stayed at zero\n"); + else + pr_err("Fail: refcount went past zero\n"); + } else { + pr_err("Fail: Zero not detected!?\n"); + } + + pr_info("attempting bad refcount_add() from zero\n"); + refcount_add(3, &zero); + + check_from_zero(&zero); +} + +static void check_saturated(refcount_t *ref) +{ + switch (refcount_read(ref)) { + case REFCOUNT_SATURATED: + pr_info("Saturation detected: still saturated\n"); + break; + case REFCOUNT_MAX: + pr_warn("Saturation detected: unsafely reset to max\n"); + break; + default: + pr_err("Fail: refcount went crazy: %d\n", refcount_read(ref)); + } +} + +/* + * A refcount_inc() from a saturated value should at most warn about + * being saturated already. + */ +void lkdtm_REFCOUNT_INC_SATURATED(void) +{ + refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED); + + pr_info("attempting bad refcount_inc() from saturated\n"); + refcount_inc(&sat); + + check_saturated(&sat); +} + +/* Should act like refcount_inc() above from saturated. */ +void lkdtm_REFCOUNT_DEC_SATURATED(void) +{ + refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED); + + pr_info("attempting bad refcount_dec() from saturated\n"); + refcount_dec(&sat); + + check_saturated(&sat); +} + +/* Should act like refcount_inc() above from saturated. */ +void lkdtm_REFCOUNT_ADD_SATURATED(void) +{ + refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED); + + pr_info("attempting bad refcount_dec() from saturated\n"); + refcount_add(8, &sat); + + check_saturated(&sat); +} + +/* Should act like refcount_inc() above from saturated. */ +void lkdtm_REFCOUNT_INC_NOT_ZERO_SATURATED(void) +{ + refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED); + + pr_info("attempting bad refcount_inc_not_zero() from saturated\n"); + if (!refcount_inc_not_zero(&sat)) + pr_warn("Weird: refcount_inc_not_zero() reported zero\n"); + + check_saturated(&sat); +} + +/* Should act like refcount_inc() above from saturated. */ +void lkdtm_REFCOUNT_ADD_NOT_ZERO_SATURATED(void) +{ + refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED); + + pr_info("attempting bad refcount_add_not_zero() from saturated\n"); + if (!refcount_add_not_zero(7, &sat)) + pr_warn("Weird: refcount_add_not_zero() reported zero\n"); + + check_saturated(&sat); +} + +/* Should act like refcount_inc() above from saturated. */ +void lkdtm_REFCOUNT_DEC_AND_TEST_SATURATED(void) +{ + refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED); + + pr_info("attempting bad refcount_dec_and_test() from saturated\n"); + if (refcount_dec_and_test(&sat)) + pr_warn("Weird: refcount_dec_and_test() reported zero\n"); + + check_saturated(&sat); +} + +/* Should act like refcount_inc() above from saturated. */ +void lkdtm_REFCOUNT_SUB_AND_TEST_SATURATED(void) +{ + refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED); + + pr_info("attempting bad refcount_sub_and_test() from saturated\n"); + if (refcount_sub_and_test(8, &sat)) + pr_warn("Weird: refcount_sub_and_test() reported zero\n"); + + check_saturated(&sat); +} + +/* Used to time the existing atomic_t when used for reference counting */ +void lkdtm_ATOMIC_TIMING(void) +{ + unsigned int i; + atomic_t count = ATOMIC_INIT(1); + + for (i = 0; i < INT_MAX - 1; i++) + atomic_inc(&count); + + for (i = INT_MAX; i > 0; i--) + if (atomic_dec_and_test(&count)) + break; + + if (i != 1) + pr_err("atomic timing: out of sync up/down cycle: %u\n", i - 1); + else + pr_info("atomic timing: done\n"); +} + +/* + * This can be compared to ATOMIC_TIMING when implementing fast refcount + * protections. Looking at the number of CPU cycles tells the real story + * about performance. For example: + * cd /sys/kernel/debug/provoke-crash + * perf stat -B -- cat <(echo REFCOUNT_TIMING) > DIRECT + */ +void lkdtm_REFCOUNT_TIMING(void) +{ + unsigned int i; + refcount_t count = REFCOUNT_INIT(1); + + for (i = 0; i < INT_MAX - 1; i++) + refcount_inc(&count); + + for (i = INT_MAX; i > 0; i--) + if (refcount_dec_and_test(&count)) + break; + + if (i != 1) + pr_err("refcount: out of sync up/down cycle: %u\n", i - 1); + else + pr_info("refcount timing: done\n"); +} diff --git a/drivers/misc/lkdtm/rodata.c b/drivers/misc/lkdtm/rodata.c new file mode 100644 index 000000000000..58d180af72cf --- /dev/null +++ b/drivers/misc/lkdtm/rodata.c @@ -0,0 +1,11 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This includes functions that are meant to live entirely in .rodata + * (via objcopy tricks), to validate the non-executability of .rodata. + */ +#include "lkdtm.h" + +void notrace lkdtm_rodata_do_nothing(void) +{ + /* Does nothing. We just want an architecture agnostic "return". */ +} diff --git a/drivers/misc/lkdtm/usercopy.c b/drivers/misc/lkdtm/usercopy.c new file mode 100644 index 000000000000..9725aed305bb --- /dev/null +++ b/drivers/misc/lkdtm/usercopy.c @@ -0,0 +1,339 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This is for all the tests related to copy_to_user() and copy_from_user() + * hardening. + */ +#include "lkdtm.h" +#include <linux/slab.h> +#include <linux/vmalloc.h> +#include <linux/sched/task_stack.h> +#include <linux/mman.h> +#include <linux/uaccess.h> +#include <asm/cacheflush.h> + +/* + * Many of the tests here end up using const sizes, but those would + * normally be ignored by hardened usercopy, so force the compiler + * into choosing the non-const path to make sure we trigger the + * hardened usercopy checks by added "unconst" to all the const copies, + * and making sure "cache_size" isn't optimized into a const. + */ +static volatile size_t unconst = 0; +static volatile size_t cache_size = 1024; +static struct kmem_cache *whitelist_cache; + +static const unsigned char test_text[] = "This is a test.\n"; + +/* + * Instead of adding -Wno-return-local-addr, just pass the stack address + * through a function to obfuscate it from the compiler. + */ +static noinline unsigned char *trick_compiler(unsigned char *stack) +{ + return stack + 0; +} + +static noinline unsigned char *do_usercopy_stack_callee(int value) +{ + unsigned char buf[32]; + int i; + + /* Exercise stack to avoid everything living in registers. */ + for (i = 0; i < sizeof(buf); i++) { + buf[i] = value & 0xff; + } + + return trick_compiler(buf); +} + +static noinline void do_usercopy_stack(bool to_user, bool bad_frame) +{ + unsigned long user_addr; + unsigned char good_stack[32]; + unsigned char *bad_stack; + int i; + + /* Exercise stack to avoid everything living in registers. */ + for (i = 0; i < sizeof(good_stack); i++) + good_stack[i] = test_text[i % sizeof(test_text)]; + + /* This is a pointer to outside our current stack frame. */ + if (bad_frame) { + bad_stack = do_usercopy_stack_callee((uintptr_t)&bad_stack); + } else { + /* Put start address just inside stack. */ + bad_stack = task_stack_page(current) + THREAD_SIZE; + bad_stack -= sizeof(unsigned long); + } + + user_addr = vm_mmap(NULL, 0, PAGE_SIZE, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_ANONYMOUS | MAP_PRIVATE, 0); + if (user_addr >= TASK_SIZE) { + pr_warn("Failed to allocate user memory\n"); + return; + } + + if (to_user) { + pr_info("attempting good copy_to_user of local stack\n"); + if (copy_to_user((void __user *)user_addr, good_stack, + unconst + sizeof(good_stack))) { + pr_warn("copy_to_user failed unexpectedly?!\n"); + goto free_user; + } + + pr_info("attempting bad copy_to_user of distant stack\n"); + if (copy_to_user((void __user *)user_addr, bad_stack, + unconst + sizeof(good_stack))) { + pr_warn("copy_to_user failed, but lacked Oops\n"); + goto free_user; + } + } else { + /* + * There isn't a safe way to not be protected by usercopy + * if we're going to write to another thread's stack. + */ + if (!bad_frame) + goto free_user; + + pr_info("attempting good copy_from_user of local stack\n"); + if (copy_from_user(good_stack, (void __user *)user_addr, + unconst + sizeof(good_stack))) { + pr_warn("copy_from_user failed unexpectedly?!\n"); + goto free_user; + } + + pr_info("attempting bad copy_from_user of distant stack\n"); + if (copy_from_user(bad_stack, (void __user *)user_addr, + unconst + sizeof(good_stack))) { + pr_warn("copy_from_user failed, but lacked Oops\n"); + goto free_user; + } + } + +free_user: + vm_munmap(user_addr, PAGE_SIZE); +} + +/* + * This checks for whole-object size validation with hardened usercopy, + * with or without usercopy whitelisting. + */ +static void do_usercopy_heap_size(bool to_user) +{ + unsigned long user_addr; + unsigned char *one, *two; + void __user *test_user_addr; + void *test_kern_addr; + size_t size = unconst + 1024; + + one = kmalloc(size, GFP_KERNEL); + two = kmalloc(size, GFP_KERNEL); + if (!one || !two) { + pr_warn("Failed to allocate kernel memory\n"); + goto free_kernel; + } + + user_addr = vm_mmap(NULL, 0, PAGE_SIZE, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_ANONYMOUS | MAP_PRIVATE, 0); + if (user_addr >= TASK_SIZE) { + pr_warn("Failed to allocate user memory\n"); + goto free_kernel; + } + + memset(one, 'A', size); + memset(two, 'B', size); + + test_user_addr = (void __user *)(user_addr + 16); + test_kern_addr = one + 16; + + if (to_user) { + pr_info("attempting good copy_to_user of correct size\n"); + if (copy_to_user(test_user_addr, test_kern_addr, size / 2)) { + pr_warn("copy_to_user failed unexpectedly?!\n"); + goto free_user; + } + + pr_info("attempting bad copy_to_user of too large size\n"); + if (copy_to_user(test_user_addr, test_kern_addr, size)) { + pr_warn("copy_to_user failed, but lacked Oops\n"); + goto free_user; + } + } else { + pr_info("attempting good copy_from_user of correct size\n"); + if (copy_from_user(test_kern_addr, test_user_addr, size / 2)) { + pr_warn("copy_from_user failed unexpectedly?!\n"); + goto free_user; + } + + pr_info("attempting bad copy_from_user of too large size\n"); + if (copy_from_user(test_kern_addr, test_user_addr, size)) { + pr_warn("copy_from_user failed, but lacked Oops\n"); + goto free_user; + } + } + +free_user: + vm_munmap(user_addr, PAGE_SIZE); +free_kernel: + kfree(one); + kfree(two); +} + +/* + * This checks for the specific whitelist window within an object. If this + * test passes, then do_usercopy_heap_size() tests will pass too. + */ +static void do_usercopy_heap_whitelist(bool to_user) +{ + unsigned long user_alloc; + unsigned char *buf = NULL; + unsigned char __user *user_addr; + size_t offset, size; + + /* Make sure cache was prepared. */ + if (!whitelist_cache) { + pr_warn("Failed to allocate kernel cache\n"); + return; + } + + /* + * Allocate a buffer with a whitelisted window in the buffer. + */ + buf = kmem_cache_alloc(whitelist_cache, GFP_KERNEL); + if (!buf) { + pr_warn("Failed to allocate buffer from whitelist cache\n"); + goto free_alloc; + } + + /* Allocate user memory we'll poke at. */ + user_alloc = vm_mmap(NULL, 0, PAGE_SIZE, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_ANONYMOUS | MAP_PRIVATE, 0); + if (user_alloc >= TASK_SIZE) { + pr_warn("Failed to allocate user memory\n"); + goto free_alloc; + } + user_addr = (void __user *)user_alloc; + + memset(buf, 'B', cache_size); + + /* Whitelisted window in buffer, from kmem_cache_create_usercopy. */ + offset = (cache_size / 4) + unconst; + size = (cache_size / 16) + unconst; + + if (to_user) { + pr_info("attempting good copy_to_user inside whitelist\n"); + if (copy_to_user(user_addr, buf + offset, size)) { + pr_warn("copy_to_user failed unexpectedly?!\n"); + goto free_user; + } + + pr_info("attempting bad copy_to_user outside whitelist\n"); + if (copy_to_user(user_addr, buf + offset - 1, size)) { + pr_warn("copy_to_user failed, but lacked Oops\n"); + goto free_user; + } + } else { + pr_info("attempting good copy_from_user inside whitelist\n"); + if (copy_from_user(buf + offset, user_addr, size)) { + pr_warn("copy_from_user failed unexpectedly?!\n"); + goto free_user; + } + + pr_info("attempting bad copy_from_user outside whitelist\n"); + if (copy_from_user(buf + offset - 1, user_addr, size)) { + pr_warn("copy_from_user failed, but lacked Oops\n"); + goto free_user; + } + } + +free_user: + vm_munmap(user_alloc, PAGE_SIZE); +free_alloc: + if (buf) + kmem_cache_free(whitelist_cache, buf); +} + +/* Callable tests. */ +void lkdtm_USERCOPY_HEAP_SIZE_TO(void) +{ + do_usercopy_heap_size(true); +} + +void lkdtm_USERCOPY_HEAP_SIZE_FROM(void) +{ + do_usercopy_heap_size(false); +} + +void lkdtm_USERCOPY_HEAP_WHITELIST_TO(void) +{ + do_usercopy_heap_whitelist(true); +} + +void lkdtm_USERCOPY_HEAP_WHITELIST_FROM(void) +{ + do_usercopy_heap_whitelist(false); +} + +void lkdtm_USERCOPY_STACK_FRAME_TO(void) +{ + do_usercopy_stack(true, true); +} + +void lkdtm_USERCOPY_STACK_FRAME_FROM(void) +{ + do_usercopy_stack(false, true); +} + +void lkdtm_USERCOPY_STACK_BEYOND(void) +{ + do_usercopy_stack(true, false); +} + +void lkdtm_USERCOPY_KERNEL(void) +{ + unsigned long user_addr; + + user_addr = vm_mmap(NULL, 0, PAGE_SIZE, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_ANONYMOUS | MAP_PRIVATE, 0); + if (user_addr >= TASK_SIZE) { + pr_warn("Failed to allocate user memory\n"); + return; + } + + pr_info("attempting good copy_to_user from kernel rodata\n"); + if (copy_to_user((void __user *)user_addr, test_text, + unconst + sizeof(test_text))) { + pr_warn("copy_to_user failed unexpectedly?!\n"); + goto free_user; + } + + pr_info("attempting bad copy_to_user from kernel text\n"); + if (copy_to_user((void __user *)user_addr, vm_mmap, + unconst + PAGE_SIZE)) { + pr_warn("copy_to_user failed, but lacked Oops\n"); + goto free_user; + } + +free_user: + vm_munmap(user_addr, PAGE_SIZE); +} + +void __init lkdtm_usercopy_init(void) +{ + /* Prepare cache that lacks SLAB_USERCOPY flag. */ + whitelist_cache = + kmem_cache_create_usercopy("lkdtm-usercopy", cache_size, + 0, 0, + cache_size / 4, + cache_size / 16, + NULL); +} + +void __exit lkdtm_usercopy_exit(void) +{ + kmem_cache_destroy(whitelist_cache); +} |